WIRELESS COMMUNICATIONS
Andrea Goldsmith
Stanford University
Copyright
c
2004 by Andrea Goldsmith
Contents
1 Overview of Wireless Communications 1
1.1 HistoryofWirelessCommunications .............................. 1
1.2 WirelessVision.......................................... 5
1.3 TechnicalIssues.......................................... 8
1.4 CurrentWirelessSystems .................................... 10
1.4.1 CellularTelephoneSystems............................... 10
1.4.2 CordlessPhones ..................................... 14
1.4.3 WirelessLANs ...................................... 15
1.4.4 WideAreaWirelessDataServices ........................... 16
1.4.5 Fixed Wireless Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.4.6 PagingSystems...................................... 17
1.4.7 Satellite Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.4.8 Bluetooth......................................... 18
1.4.9 HomeRF ......................................... 19
1.4.10 OtherWirelessSystemsandApplications ....................... 19
1.5 TheWirelessSpectrum ..................................... 20
1.5.1 MethodsforSpectrumAllocation............................ 20
1.5.2 SpectrumAllocationsforExistingSystems ...................... 20
1.6 Standards ............................................. 21
2 Path Loss and Shadowing 25
2.1 Radio Wave Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.2 Transmit and Receive Signal Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.3 Free-SpacePathLoss....................................... 29
2.4 RayTracing............................................ 30
2.4.1 Two-RayModel ..................................... 31
2.4.2 DielectricCanyon(Ten-RayModel).......................... 34
2.4.3 GeneralRayTracing................................... 35
2.5 SimplifiedPathLossModel ................................... 38
2.6 EmpiricalPathLossModels................................... 40
2.6.1 Okumura’sModel .................................... 40
2.6.2 HataModel........................................ 41
2.6.3 COST231ExtensiontoHataModel .......................... 41
2.6.4 Walfisch/BertoniModel ................................. 42
2.6.5 Piecewise Linear (Multi-Slope) Model . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.6.6 Indoor Propagation Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
iii
2.7 ShadowFading .......................................... 44
2.8 CombinedPathLossandShadowing.............................. 47
2.9 Outage Probability under Path Loss and Shadowing . . . . . . . . . . . . . . . . . . . . . 47
2.10CellCoverageArea........................................ 48
3 Statistical Multipath Channel Models 63
3.1 Time-VaryingChannelImpulseResponse ........................... 63
3.2 Narrowbandfadingmodels ................................... 68
3.2.1 Autocorrelation,CrossCorrelation,andPowerSpectralDensity........... 69
3.2.2 EnvelopeandPowerDistributions ........................... 74
3.2.3 LevelCrossingRateandAverageFadeDuration ................... 76
3.2.4 FiniteStateMarkovModels............................... 78
3.3 WidebandFadingModels .................................... 79
3.3.1 PowerDelayProfile ................................... 82
3.3.2 CoherenceBandwidth .................................. 84
3.3.3 DopplerPowerSpectrumandChannelCoherenceTime ............... 86
3.3.4 Transforms for Autocorrelation and Scattering Functions . . . . . . . . . . . . . . 87
3.4 Discrete-TimeModel....................................... 88
3.5 Spatio-TemporalModels..................................... 89
4 Capacity of Wireless Channels 97
4.1 Introduction............................................ 97
4.2 CapacityinAWGN........................................ 98
4.3 CapacityofFlat-FadingChannels................................ 99
4.3.1 ChannelandSystemModel............................... 99
4.3.2 NoChannelInformation................................. 100
4.3.3 ChannelDistributionInformation(CDI)Known ................... 101
4.3.4 Channel Side Information at Receiver . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.3.5 Channel Side Information at the Transmitter and Receiver . . . . . . . . . . . . . 104
4.3.6 Capacity with Receiver Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.3.7 CapacityComparisons.................................. 111
4.4 CapacityofFrequency-SelectiveFadingChannels....................... 113
4.4.1 Time-InvariantChannels ................................ 113
4.4.2 Time-VaryingChannels ................................. 115
5 Digital Modulation and Detection 125
5.1 SignalSpaceAnalysis ...................................... 126
5.1.1 SignalandSystemModel ................................ 126
5.1.2 GeometricRepresentationofSignals .......................... 127
5.1.3 Receiver Structure and Sufficient Statistics . . . . . . . . . . . . . . . . . . . . . . 130
5.1.4 Decision Regions and the Maximum Likelihood Decision Criterion . . . . . . . . . 133
5.1.5 Error Probability and the Union Bound . . . . . . . . . . . . . . . . . . . . . . . . 135
5.2 PassbandModulationPrinciples ................................ 140
5.3 AmplitudeandPhaseModulation ............................... 140
5.3.1 PulseAmplitudeModulation(MPAM)......................... 142
5.3.2 PhaseShiftKeying(MPSK) .............................. 143
5.3.3 QuadratureAmplitudeModulation(MQAM)..................... 145
5.3.4 DifferentialModulation ................................. 146
5.3.5 ConstellationShaping .................................. 149
5.3.6 QuadratureOffset .................................... 150
5.4 FrequencyModulation...................................... 150
5.4.1 Frequency Shift Keying (FSK) and Minimum Shift Keying (MSK) . . . . . . . . . 151
5.4.2 Continuous-PhaseFSK(CPFSK)............................ 152
5.4.3 NoncoherentDetectionofFSK ............................. 153
5.5 PulseShaping........................................... 154
5.6 SymbolSynchronizationandCarrierPhaseRecovery..................... 157
5.6.1 Receiver Structure with Phase and Timing Recovery . . . . . . . . . . . . . . . . . 157
5.6.2 MaximumLikelihoodPhaseEstimation ........................ 159
5.6.3 Maximum-Likelihood Timing Estimation . . . . . . . . . . . . . . . . . . . . . . . 161
6 Performance of Digital Modulation over Wireless Channels 171
6.1 AWGNChannels......................................... 171
6.1.1 Signal-to-NoisePowerRatioandBit/SymbolEnergy................. 171
6.1.2 Error Probability for BPSK and QPSK . . . . . . . . . . . . . . . . . . . . . . . . 172
6.1.3 Error Probability for MPSK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
6.1.4 Error Probability for MPAM and MQAM . . . . . . . . . . . . . . . . . . . . . . . 175
6.1.5 Error Probability for FSK and CPFSK . . . . . . . . . . . . . . . . . . . . . . . . 177
6.1.6 Error Probability Approximation for Coherent Modulations . . . . . . . . . . . . . 178
6.1.7 Error Probability for Differential Modulation . . . . . . . . . . . . . . . . . . . . . 178
6.2 Alternate Q FunctionRepresentation.............................. 180
6.3 Fading............................................... 180
6.3.1 Outage Probability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
6.3.2 Average Probability of Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
6.3.3 Moment Generating Function Approach to Average Error Probability . . . . . . . 184
6.3.4 Combined Outage and Average Error Probability . . . . . . . . . . . . . . . . . . . 188
6.4 DopplerSpread.......................................... 189
6.5 IntersymbolInterference..................................... 191
7Diversity 203
7.1 RealizationofIndependentFadingPaths............................ 203
7.2 DiversitySystemModel ..................................... 204
7.3 SelectionCombining ....................................... 206
7.4 ThresholdCombining ...................................... 208
7.5 MaximalRatioCombining.................................... 211
7.6 Equal-GainCombining...................................... 212
7.7 MomentGeneratingFunctionsinDiversityAnalysis ..................... 214
7.7.1 DiversityAnalysisforMRC............................... 214
7.7.2 DiversityAnalsysiforEGCandSC .......................... 218
7.7.3 Diversity Analysis for Noncoherent and Differentially Coherent Modulation . . . . 218
7.8 TransmitterDiversity ...................................... 218
